curriculum/challenges/english/blocks/learn-functional-programming-by-building-a-spreadsheet/643498755d54c6279ba09078.md
Most spreadsheet programs include built-in functions for calculation.
Declare a sum function that takes a nums parameter, which will be an array of numbers. It should return the result of calling reduce on the array to sum all of the numbers.
You should declare a sum variable.
assert.match(code, /(?:let|const|var)\s+sum/);
You should use const to declare your sum variable.
assert.match(code, /const\s+sum/);
Your sum variable should be a function.
assert.isFunction(sum);
Your sum function should use arrow syntax.
assert.match(code, /const\s+sum\s*=\s*(\([^)]*\)|[^\s()]+)\s*=>/);
Your sum function should have a nums parameter.
assert.match(code, /const\s+sum\s*=\s*(\(\s*nums\s*\)|nums)\s*=>/);
Your sum function should use an implicit return.
assert.notMatch(code, /const\s+sum\s*=\s*(\(\s*nums\s*\)|nums)\s*=>\s*{/);
Your sum function should return the result of calling .reduce() on nums.
assert.match(code, /const\s+sum\s*=\s*(\(\s*nums\s*\)|nums)\s*=>\s*nums\.reduce\(/);
Your sum function should return the sum of all numbers in nums.
const numbers = [1, 2, 3, 4, 5];
assert.equal(sum(numbers), 15);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1" />
<link rel="stylesheet" href="./styles.css" />
<title>Functional Programming Spreadsheet</title>
</head>
<body>
<div id="container">
<div></div>
</div>
<script src="./script.js"></script>
</body>
</html>
#container {
display: grid;
grid-template-columns: 50px repeat(10, 200px);
grid-template-rows: repeat(11, 30px);
}
.label {
background-color: lightgray;
text-align: center;
vertical-align: middle;
line-height: 30px;
}
--fcc-editable-region--
--fcc-editable-region--
const range = (start, end) => Array(end - start + 1).fill(start).map((element, index) => element + index);
const charRange = (start, end) => range(start.charCodeAt(0), end.charCodeAt(0)).map(code => String.fromCharCode(code));
window.onload = () => {
const container = document.getElementById("container");
const createLabel = (name) => {
const label = document.createElement("div");
label.className = "label";
label.textContent = name;
container.appendChild(label);
}
const letters = charRange("A", "J");
letters.forEach(createLabel);
range(1, 99).forEach(number => {
createLabel(number);
letters.forEach(letter => {
const input = document.createElement("input");
input.type = "text";
input.id = letter + number;
input.ariaLabel = letter + number;
container.appendChild(input);
})
})
}